IMO all of the CAI Systems on the market today,they all do the same thing I don't think one is any better than the next.It all depends on what you are looking for in a CAI and what you are looking to spend.For me I 'm running K&N in all of my Rides.

I seen the Green filters down at the 4-wheel jamboree and they are no different that a K&N. Neither one filters very well due to the gauze material they are made of. Hold either one up to the light and you will see all the holes in them.

I seen the Green filters down at the 4-wheel jamboree and they are no different that a K&N. Neither one filters very well due to the gauze material they are made of. Hold either one up to the light and you will see all the holes in them.

Some air filter companies tout their high filtration levels in the 99th percentile. Doesn't higher filtration mean a better air filter?

No. The quality of an air filter can only be judged by reviewing all four important characteristics. 1) Restriction while loading with dust; 2) Filtration efficiency as a percentage; 3) Dust holding capacity before the filter needs cleaning or replacement ; and 4) filter life. Any company designing an air filter must make choices about these four characteristics and how their filter will perform in each area. Generally speaking, each characteristic of an air filter has an inverse relationship to at least one of the others, meaning, as filtration efficiency goes up, restriction increases and capacity or service life decreases. So an air filter manufacturer can design an air filter to have ultra high filtration efficiency by compromising the filters restriction, capacity, and/or service life. We judge the quality of an air filter based upon the proper balance of these four essential criteria. Maximizing one at the expense of others sounds more like a marketing goal rather than an engineering goal. So the basic answer to the original question is that higher filtration is not necessarily a good thing when it comes at the expense of restriction, reusability and/or capacity. While the benefits of a filter with 99.9% filtration are unknown, the benefits of low restriction are measurable and clear. Low restriction helps an engine perform more efficiently generating more power and torque.

That would lead a reasonable person to ask what then is a safe level of filtration. This question is literally unanswered. Minimum air filter specifications are generally not called out in vehicle owners' manuals, nor will you find much published information on air filtration requirements from vehicle manufacturers. We have never seen a scientific study concluding what levels of filtration efficiency correspond to various levels of engine wear. Some large air filter companies do not even publish information on the efficiencies of the air filters they manufacture. It is K&N's opinion that both the Fine and Coarse Test Dust mixtures used in air filter testing contain such a high concentration of small particles that even filtration efficiency numbers as low as 90% may provide adequate engine protection. Remember that almost 11% of COARSE test dust is smaller than 5.5 microns (the size of a red blood cell). For a detailed explanation of our testing protocol, click here.

The fact is that an engine is not a pristine environment. Fuel enters after passing through a fuel filter, combines with air which is ignited to explode in a pressurized chamber. The combustion is not 100% efficient and leaves residues behind that must be flushed from the engine. Engines have tolerances or measured gaps between surface areas. While there are few if any studies on engine wear, it would seem reasonable to speculate that particles less than 5.5 microns create little engine wear unless ingested at very high levels of concentration. As support for this theory, consider the filtration levels provided by fuel filters and oil filters that sometimes tout their ability to filter particles above 10 or 20 microns.

If you really want to compare two air filters, you need to know all four characteristics mentioned above. Consumers can then choose what matters most to them. But comparing two air filters with only one piece of information is like saying a bicycle is better than a car based solely on a comparison of mileage. Yes the mileage is better, but a car has a few other benefits (speed, comfort, keeps you dry in wet weather) that just may offset the mileage disadvantage.

We design air filters to provide low restriction throughout the filter's service interval. We seek the best balance between airflow and filtration recognizing they are inversely related. After nearly 40 years in business with millions of air filters sold, we have a track record you can trust and the experience that can only be earned through years of focusing on just one thing. But even our experience is not enough. We operate a fully staffed air filtration lab that operates on a year round basis with two test stands. The lab was designed by Southwest Research and is calibrated regularly to ensure our test results are reliable. This testing is an essential ingredient in verifying our air filters meet our own high standards of excellence. Making a great air filter is no accident and we are confident our air filters provide outstanding engine protection with huge air flow advantages throughout the air filter's service interval. That's why we back up our replacement air filters with both a Million Mile Warranty and our Consumer Protection Pledge.

K&N's air filtration lab tests air filters according to ISO5011 test protocol. The ISO (International Organization for Standardization) is an international organization which establishes standards used by different industries worldwide. The ISO does not establish any standards for an air filter's effectiveness; they establish standards for the testing procedures used to find air filters' capacities and efficiencies only under the fixed and chosen parameters of the test being conducted. In the case of engine air filters, the ISO5011 test ensures consistency in the procedure used to test a filter's initial restriction, initial efficiency, cumulative (full-life) efficiency, and dust holding capacity. Using a standardized test procedure and disclosing the user selected variables ensures the same test can be run anywhere around the world. Some of the requirements of the ISO5011 test procedure are that the temperature of the test lab must be maintained at 23 degrees Celsius +/- 5 degrees Celsius, and the relative humidity of the test lab must be maintained at 55% +/- 15%, for the entire duration of the test. During the test at each weighing stage (when the mass of the filter is found) the humidity can only vary +/- 2%. Also, all test dust which is fed into the air filter must be "found" after the test is completed. That means if 10 grams of test dust is fed to the filter during the test, but only 8 grams of dust is found trapped in the filter after the test, part of the ISO5011 test procedure requires that the remaining 2 grams of dust must be found. The dust could be in the air filter housing, the air duct, or the absolute filter which traps any dust that passes through the air filter, but wherever it is it must be accounted for. If any of the requirements of the ISO test procedure are not met, the test is not valid. A company's participation in testing using ISO5011 test procedures is strictly voluntary. Conducting an ISO5011 test requires a considerable investment in both time and equipment, and many air filter companies simply do not have the resources to complete an ISO test in-house. K&N views this test procedure as a valuable part of our research and development process.

IMO all of the CAI Systems on the market today,they all do the same thing I don't think one is any better than the next.It all depends on what you are looking for in a CAI and what you are looking to spend.For me I 'm running K&N in all of my Rides.

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I agree. I have had AirAID in 3 of my rigs, and thats all I ever plan on running. I really think its up to personal preference.

I seen the Green filters down at the 4-wheel jamboree and they are no different that a K&N. Neither one filters very well due to the gauze material they are made of. Hold either one up to the light and you will see all the holes in them.

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x2. save you money and change your filter once a year. i run k&n's in all my trucks. all they do is destroy the maf sensor by coating it with oil.

We are aware of the “urban myth” (K&N News Story) created by a few dealerships that a vehicle's MAF sensor can be contaminated by K&N filter oil. No evidence has ever been provided to support this “myth” and three years of diagnostic testing by K&N has shown that not only is this allegation not real, it is not even possible. In our opinion, it is an excuse for a dealership and/or the vehicle manufacturer to avoid a legitimate warranty repair. In the last 4 years, we have sold over 10,000,000 lifetime air filters and received only a few hundred calls from consumers who are having dealership or service provider challenges. We believe that Dealership's or service provider's real incentive may be to discourage the use of reusable products so they can sell disposable products over and over. In order to provide consumers with added comfort that they will not be placed in a bad position by an improper warranty denial, we offer our Consumer Protection Pledge.

The oil treatment on our cotton is very small (usually less than 2 ounces) and is a critical component of our filtration technology. There is nothing unusual about the use of oil as a tacking agent to improve air filter efficiency. In fact, certain Ford Motorcraft and Fram disposable air filters are treated with oil. This make us wonder if it is only the oil treatment from reusable lifetime air filters that is alleged cause a vehicle problem? The idea that oil comes off our filter throughout its life is truly ridiculous. Just like oil treated disposable air filters, once our oil is properly and evenly absorbed through the cotton, no oil will come off, even under extreme engine conditions. We have even conducted a test with an over oiled K&N air filter in which we flowed 1,000 cubic feet of air per minute for over twelve hours (few cars or truck could generate even 500 cubic feet of air flow). The use of an absolute filter confirmed that no oil came off the K&N filter tested, even in these harsh conditions.

We have tested many MAF sensors claimed to be damaged. We can fully diagnose their condition and likely cause of failure. For a full discussion of our MAF sensor test protocol and findings, see K&N Mass Air Flow Testing Results and Findings.

Not one of these suspected MAF sensors sent in for laboratory evaluation was shown to have failed due to contamination from K&N filter oil.

We are the solution

We are so confident about our testing and the quality of our product that we offer a Consumer Protection Pledge. So if you ever get in a bind with a dealership, call us because we are the solution.

Other Information:
An In-Depth Look at How Mass Air Flow Sensors Work

And for the record I do not use K&N filters and I am not compensated by them or any other company I just don't like seeing misinformation perpetuated.